THE SALTWORKS. 179 boiling within the huts; but the salt so obtained is darker in colour and less pure. The skill of the women consists in mixing the earth and water in the right proportions just before the filtering begins.

Bad weather and continued rain greatly interfere with the salt manufacture, for the soil then becomes saturated with moisture, and in that state is not suitable for the extraction of salt. At such times the people break down the sides of the ravine, for they also contain a high percentage of saline matter. It is, of course, self-evident that this continual drain upon the layers of the ravine-bottom must result in its gradual lowering. At the present time the walls have an average height of thirty to fifty feet, showing the extent to which human agency . has utilised the saline deposits contained in the soil.

It would be interesting to know whether the yield of salt undergoes any proportionate variation as the ravine gets deeper ; for this would decide the question whether the salt, as the native workers maintain, comes from the water of the hot springs or not. J am myself inclined to think that these springs have no connexion with the supply of salt except that of opening up the layers of earth in which it is contained. The rocks from among which the springs issue are primitive rocks ; the salt itself must lie in the alluvial soil, just as it does at Rejaf and at Gondokoéro. At all events, the people of Kibiro affirm that when the water of the springs is cooled by heavy rains, and the soil is consequently charged with moisture, they are unable to carry on the process for the extraction of the salt. But the same is true at Rejaf, where no hot springs exist. It is much more reasonable to suppose that the rain washes the salt out of the soil, and consequently the saline liquor is too thin to deposit much salt.

The salt of Kibiro is coarse-grained, and mostly of a rather dark grey colour, which is due to the process of manufacture. It has a faintly bitter after-taste—a fact also noticed by the Negroes.

Kabréga once sent me as a present of especial value a packet of salt of a dark grey colour, but very pure in saline properties, which he obtained from Hamgurko, on the river of Usongora "(the Duéru). The bitter taste that characterises the salt of